OVERCONSOLIDATION OF ALLUVIAL CLAYS

概要

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Alluvial clay, widely distributed throughout the world, is generally in an overconsolidated state. The phenomenon occurs in spite of the fact that the clay has not undergone stress release. This is attributed to development of an additional structure induced by aging. In this paper, the overconsolidated state of three alluvial clays found in Tokyo Bay, Singapore, and the Arabian Gulf are presented as well as a discussion of the causes of overconsolidation and the formation process of each clay.Characteristics of overconsolidation caused by aging such as secondary compression, chemical bonding, and desiccation stress are first discussed. Effective overburden stress, σ^^-_<υo>, consolidation critical stress, σ^^-_c, and overconsolidation ratio, OCR, of the three clays are presented. Causes of overconsolidation and the formation process of each clay are evaluated from 1) the σ^^-_<υo>-σ^^-_c-OCR relationship, and 2) the changes in sea level from deposition to the present. It is concluded that 1) chemical bonding, 2) secondary compression, 3) cementation, 4) oxidation, and 5) desiccation stress are the causes of overconsolidation in the three clays.
1983-12-15